This application incorporates by reference in their entirety U.S. Pat. No. 9,128,106 B2, issued Sep. 8, 2015, and the following publication: Determination of N-nitrosamines by automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometry, Mousa Amayreh, Basheer Chanbasha, Khalid Alhooshani, Nuhu Dalhat Mu'azu, and Hian Kee Lee, J. Sep. Sci. 2015, 38, 1741-1748.